Planning and control for magnetic resonance guided radiation therapy

ABSTRACT

Magnetic resonance (MR) guided radiation therapy (MRgRT) enables control over the delivery of radiation based on patient motion indicated by MR imaging (MRI) images captured during radiation delivery. A method for MRgRT includes: simultaneously using one or more radiation therapy heads to deliver radiation and an MRI system to perform MRI; using a processor to determine whether one or more gates are triggered based on at least a portion of MRI images captured during the delivery of radiation; and in response to determining that one or more gates are triggered based on at least a portion of the MRI images captured during the delivery of radiation, suspending the delivery of radiation.

RELATED APPLICATION

This application claims priority under 35 U.S.C. §119(e) to U.S.Provisional Patent Application No. 62/115,105, entitled PLANNING ANDCONTROL FOR MAGNETIC RESONANCE GUIDED RADIATION THERAPY and filed onFeb. 11, 2015, the disclosure of which is incorporated herein byreference in its entirety.

TECHNICAL FIELD

The subject matter described herein relates to radiation therapy andmore particularly to magnetic resonance guided radiation therapy(MRgRT).

RELATED ART

Radiation therapy is frequently used to control and eliminate malignantcells in a patient. For example, a cancerous tumor can be exposed toradiation (e.g., X-rays, gamma rays, and charged particles) during oneor more treatment sessions. The effectiveness of radiation therapydepends upon delivering an adequate dose of radiation to a region ofinterest (ROI), which can include the cancerous tumor as well as areasof potential disease spread. At the same time, the radiation should bedelivered in a manner that spares organs at risk (OARs).

Conventionally, radiation therapy treatments are planned andadministered based on the contours and positions of ROIs and OARs asdefined in static medical imaging scans (e.g., computed tomography (CT),magnetic resonance imaging (MRI)). Thus, conventional radiation therapydoes not account for patient motion during treatment. For example,patient organ geometry may shift significantly during treatment due tovoluntary and/or involuntary movements (e.g., respiration, musclecontractions). Consequently, the actual dose of radiation delivered tothe ROI and the extent to which OARs are subject to radiation are likelyto deviate from the intended treatment plan. As such, conventionalradiation therapy can be less effective than desirable.

SUMMARY

Systems and methods for MRgRT are provided. Implementations of thecurrent subject matter improve the administration of radiation therapyincluding by simultaneously delivering radiation and performing MRI. Thedelivery of radiation can be controlled based on patient motionindicated by MRI images captured during the delivery or radiation. Oneor more mechanisms can be deployed during the delivery of radiation toterminate radiation delivery based on patient motion.

Implementations of the current subject matter include a method forMRgRT. The method can include: simultaneously using one or moreradiation therapy heads to deliver radiation and an MRI system toperform MM; using a processor to determine whether one or more gates aretriggered based on at least a portion of MRI images captured during thedelivery of radiation; and in response to determining that one or moregates are triggered based on at least a portion of the MM imagescaptured during the delivery of radiation, suspending the delivery ofradiation.

Implementations of the current subject matter include a system forMRgRT. The system can include an MRgRT apparatus and a processor coupledto the MRgRT apparatus.

The MRgRT apparatus can include one or more radiation therapy heads andan MRI system. The MRgRT apparatus can be configured to simultaneouslyuse the one or more radiation therapy heads to deliver radiation and theMRI system to perform MRI.

The processor can be configured to: determine whether one or more gatesare triggered based on at least a portion of MRI images captured duringthe delivery of radiation; and in response to determining that one ormore gates are triggered based on at least a portion of the MRI imagescaptured during the delivery of radiation, suspend the delivery ofradiation.

Implementations of the current subject matter include a method forMRgRT. The method can include: receiving a plurality of MRI imagescaptured by an MRI system during a delivery of radiation by one or moreradiation therapy heads; determining, based on a least a portion of theMRI images, whether one or more gates are triggered; and in response todetermining that the one or more gates are triggered based on at least aportion of the MRI images, causing the one or more radiation therapyheads to suspend delivery of radiation.

Implementations of the current subject matter can include, but are notlimited to, methods consistent with the descriptions provided herein aswell as articles that comprise a tangibly embodied machine-readablemedium operable to cause one or more machines (e.g., computers, etc.) toresult in operations implementing one or more of the described features.Similarly, computer systems are also described that may include one ormore processors and one or more memories coupled to the one or moreprocessors. A memory, which can include a non-transitorycomputer-readable or machine-readable storage medium, may include,encode, store, or the like one or more programs that cause one or moreprocessors to perform one or more of the operations described herein.Computer implemented methods consistent with one or more implementationsof the current subject matter can be implemented by one or more dataprocessors residing in a single computing system or multiple computingsystems. Such multiple computing systems can be connected and canexchange data and/or commands or other instructions or the like via oneor more connections, including but not limited to a connection over anetwork (e.g. the Internet, a wireless wide area network, a local areanetwork, a wide area network, a wired network, or the like), via adirect connection between one or more of the multiple computing systems,etc.

The details of one or more variations of the subject matter describedherein are set forth in the accompanying drawings and the descriptionbelow. Other features and advantages of the subject matter describedherein will be apparent from the description and drawings, and from theclaims. While certain features of the currently disclosed subject matterare described for illustrative purposes in relation to radiationtherapy, it should be readily understood that such features are notintended to be limiting. The claims that follow this disclosure areintended to define the scope of the protected subject matter.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are incorporated in and constitute apart of this specification, show certain aspects of the subject matterdisclosed herein and, together with the description, help explain someof the principles associated with the disclosed implementations. In thedrawings,

FIG. 1 is a network diagram illustrating an MRgRT system consistent withimplementations of the current subject matter;

FIG. 2 is a cross-sectional view illustrating an MRgRT apparatusconsistent with implementations of the current subject matter;

FIG. 3 illustrates a series of MRI images consistent withimplementations of the current subject matter;

FIG. 4A illustrates the delivery of one or more radiation beamsconsistent with implementations of the current subject matter;

FIG. 4B illustrates the delivery of one or more radiation beamsconsistent with implementations of the current subject matter;

FIG. 5 is a flowchart illustrating an MRgRT process consistent withimplementations of the current subject matter;

FIG. 6 is a flowchart illustrating a process for treatment planningconsistent with implementations of the current subject matter;

FIG. 7 is a flowchart illustrating a process for administering radiationtherapy consistent with implementations of the current subject matter;

FIG. 8 is a flowchart illustrating a process for dose computationconsistent with implementations of the current subject matter; and

FIG. 9 is a flowchart illustrating a process for administering radiationtherapy consistent with implementations of the current subject matter.

DETAILED DESCRIPTION

Conventional approaches for administering radiation therapy generally donot account for patient motion during radiation delivery. The isocenterplacement and beam configuration are generally performed duringtreatment planning on the basis of static images (e.g., MRI, CT).However, shifts in patient organ geometry are likely to occur duringtreatment.

For example, respiration and muscle contractions can deform the contoursof anatomical structures (e.g., ROIs, OARs) as well as change theirpositions. As a result, an ROI can move outside of the paths ofradiation beams as set forth in the original treatment plan therebyreducing the actual dose of radiation delivered to the area. Similarly,an OAR may move into the paths of radiation beams and be subjected to anunintended amount radiation.

Various implementations of the current subject matter can includesystems and methods for MRgRT that provide dynamic controls for thedelivery of radiation. Implementations of the current subject matter caninclude a gating mechanism which imposes one or more spatial and/ortemporal gates for controlling the delivery of radiation. Someimplementations of the current subject matter can further include aninterlock mechanism, which detects gross patient movement and suspendsradiation delivery accordingly. Gating and interlock mechanismsconsistent with the present disclosure can operate based on MRI images(e.g., planar, volumetric) including MM images captured during thedelivery of radiation.

FIG. 1 is a system diagram illustrating an MRgRT system 100 consistentimplementations of the current subject matter. Referring the FIG. 1, theMRgRT system 100 can include a system controller 112, a gantry 120, aradiation therapy head 122, a patient couch 124, a multi-leaf collimator126, and an MRI system 128.

The system controller 112 is configured to control the operations of thegantry 120, the radiation therapy head 122, the patient couch 124, themulti-leaf collimator 126, and the MRI system 128. The system controller112 can be coupled to a control console 114. Via the control console114, a user may control the operations of the system controller 112thereby controlling the operations of one or more of the gantry 120, theradiation therapy head 122, the patient couch 124, the multi-leafcollimator 126, and the MRI system 128.

During a radiation therapy session, the radiation therapy head 122 maydeliver one or more beams of radiation. The system controller 112 mayrotate the gantry 120 and/or the patient couch 124 such that a patienton the patient couch 124 is properly positioned to receive the radiationbeams (e.g., at an ROI) from the radiation therapy head 122.

The radiation therapy head 122 can be implemented by any device that canbe a source of radiation or a linear particle accelerator (LINAC)without departing from the scope of the present disclosure. For example,the radiation therapy head 122 can be a radioisotope source usingisotopes including, for example, but not limited to, cobalt (e.g.,cobalt-60 (⁶⁰Co)) and iridium (e.g., iridium-192 (¹⁹²Ir)). Alternatelyor in addition, the radiation therapy head 122 can also provide particletherapy as an LINAC. Furthermore, although the MRgRT system 100 is shownto include a single radiation therapy head, the MRgRT system 100 caninclude additional radiation therapy heads without departing from thescope of the present disclosure.

In some implementations of the current subject matter, the MRgRT system100 may administer intensity modulated radiation therapy (IMRT) orconformal radiation therapy (CRT). As such, the system controller 112may engage the multi-leaf collimator 126. The multi-leaf collimator 126includes a plurality of “leaves” of heavy metal material (e.g., lead(Pb), tungsten (W)) that alter the shape of the radiation beam from theradiation therapy head 122 by blocking at least some portions of theradiation beam. The shape of the radiation beam can be adjusted (e.g.,via the system controller 112) by changing the configuration of theleaves in the multi-leaf collimator 126. It is to be understood thatreferences to radiation therapy throughout the present disclosurecontemplates a variety of different types and forms of radiation therapyincluding, for example, but not limited to, IMRT and CRT.

In some examples, the system controller 112, the control console 114,the gantry 120, the radiation therapy head 122, the patient couch, themulti-leaf collimator 126, and the MRI system 128 can be part of anMRgRT apparatus 110 capable of simultaneously delivering radiation andperforming MRI. The MRgRT apparatus 110 is described in further detailin co-owned U.S. Pat. No. 7,907,987, the disclosure of which isincorporated herein by reference in its entirety.

The MRI system 128 captures planar (i.e., 2-dimensional (2D)) and/orvolumetric (i.e., 3-dimensional (3D)) MRI images. The MRI system 128 canbe configured to capture MRI images of the patient during the deliveryof radiation. The MRI system 128 can also capture MRI images as part ofmotion-based treatment planning and throughout the course of radiationtherapy treatment. For example, the MRI system 128 may capture planarand/or volumetric MM images at a certain rate (e.g., 4 frames persecond). Advantageously, a sequential series of planar and/or volumetricMRI images captured by the MM system 128 during the delivery ofradiation enables tracking of patient motions (e.g., shift in patientorgan geometry) during the delivery of radiation. The MRI system 128 canstore such data (e.g., 4-dimensional (4D) MRI image data) in a firstdata store 142.

The MRgRT system 100 includes a user interface system 130. The userinterface system 130 can provide one or more input/output (I/O)mechanisms including, for example, but not limited to, a display 132, ascanner 134, a printer 136, and a security reader 138. A user (e.g., aradiotherapist) can interact with the MRgRT system 100 via the one ormore I/O mechanisms. For example, the user can be authenticated toaccess the MRgRT system 100 via the security reader 138 using one ormore mechanisms including, for example, but not limited to, biometricsand radio frequency identification (RFID) tags. The user can alsoconfigure the MRgRT system 100 via the user interface system 130 toperform one or more operations associated with the administration ofradiation therapy including, for example, but not limited to, treatmentplanning, execution, and optimization.

The MRgRT system 100 can further include a processor 150, which canmonitor for when gates are triggered and/or when interlock thresholdsare exceeded based on MRI images (e.g., 4D) captured by the MRI system128 during radiation delivery. The processor 150 can also be configuredto generate and/or modify one or more treatment plans. In addition, theprocessor 150 can calculate the actual dose of radiation that wasdelivered a patient during a radiation therapy treatment session basedon the MRI images captured during the delivery of radiation. The actualdose of radiation that was delivered to the patient can be affected bypatient motion (e.g., change in patient organ geometry) during thedelivery of radiation as well as interruptions to radiation deliverycaused by the gating mechanism and/or the interlocking mechanism.

The MRgRT system 100 can also be configured to track the cumulative doseof radiation delivered to a patient. As such, the processor 150 mayaccrue the actual dose of radiation delivered to a patient duringindividual radiation therapy treatment sessions.

In some implementations of the current subject matter, the MRgRT system100 can provide a patient monitoring and communication system 162. Forexample, the patient monitoring and communication system 162 can includea camera and/or a microphone. The MRgRT system 100 can further include apatient audio/video (A/V) entertainment system 164. For example, thepatient A/V entertainment system 164 can be portable electronic devicesuch as a tablet personal computer (PC).

The MRgRT system 100 supports access by a plurality of remote usersincluding, for example, but not limited to, a first remote user 192, asecond remote user 194, and a third remote user 196. Remote users mayaccess the MRgRT system 100 via a wired and/or wireless network 170 toperform tasks including, for example, but not limited to, radiationtherapy treatment planning, approvals, and scheduling. Access to theMRgRT system 100 by remote users can be monitored and regulated by afirewall 180. The MRgRT system 100 can include additional and/ordifferent components than shown without departing from the scope of thepresent disclosure.

FIG. 2 is a cross-sectional view illustrating the MRgRT apparatus 110consistent with implementations of the current subject matter. Referringto FIGS. 1 and 2, the MRgRT apparatus 110 includes the gantry 120, themulti-leaf collimator 126, the patient couch 124, and the MRI system128. Consistent with implementations of the current subject matter, apatient 200 can be placed on the patient couch 124. The patient 200 canreceive radiation from the radiation therapy head 122 while the MRIsystem 128 simultaneously captures one or more MRI images of the patient200. The MRgRT apparatus 110 can include additional and/or differentcomponents than shown without departing from the scope of the presentdisclosure.

FIG. 3 illustrates a series 300 of MRI images consistent withimplementations of the current subject matter. Referring to FIGS. 1, 2,and 3, the series 300 of MRI images depict patient motion, such asduring the delivery of radiation. The MRgRT system 100 (e.g., the MRIsystem 128) can capture the MRI images of the series 300 as part ofmotion-based treatment planning, while a patient is undergoing radiationtherapy, and/or throughout the course of radiation therapy treatment. Asshown, the series 300 includes a first MRI image 310, a second MRI image320, a third MRI image 330, and a fourth MRI image 340.

A change in the patient's organ geometry resulting from a musclecontraction is depicted in the first MRI image 310 and the second MRIimage 320. For example, as shown in the first MRI image 310 and thesecond MRI image 320, a contraction of the patient's gluteus musclesresults in a shift in the position of the bladder 352.

A change in the patient's organ geometry resulting from respiration isdepicted in the third MRI image 330 and the fourth MRI image 340. Forexample, as shown in the third MRI image 330 and the fourth MRI image340, taking a breath causes a shift in the positions of the bladder 352,the prostate 354, and the rectum 356.

FIG. 4A illustrates the delivery of one or more radiation beamsconsistent with implementations of the current subject matter. Referringto FIG. 4A, a patient's radiation therapy treatment can includedelivering a plurality of radiation beams to an ROI 410, including, forexample, a first radiation beam 422 and a second radiation beam 424. Thepatient's radiation therapy treatment can be planned by placing thefirst radiation beam 422 and the second radiation beam 424 such that theROI 410 is subject to maximum exposure to the first radiation beam 422and the second radiation beam 424. Moreover, the patient's radiationtherapy treatment can be planned by placing the first radiation beam 422and the second radiation beam 424 such that a first OAR 432 and a secondOAR 434 are subject to minimal exposure to the first radiation beam 422and the second radiation beam 424.

FIG. 4B illustrates the delivery of one or more radiation beamsconsistent with implementations of the current subject matter. Referringto FIGS. 4A-B, patient motion during radiation therapy can changepatient organ geometry and cause the delivery of radiation beams todeviate from the treatment plan.

For example, as shown in FIG. 4B, patient motion during radiationtherapy may cause the ROI 410 to shift outside of the paths of the firstradiation beam 422 and the second radiation beam 424 as placed inaccordance with the treatment plan. Alternately or in addition, patientmotion during radiation therapy may cause the second OAR 434 to shiftinto the paths of the first radiation beam 422 and the second radiationbeam 434 as placed in accordance with the treatment plan. As a result,the actual dose of radiation delivered to the ROI 410 is less thanplanned while the second OAR 434 is exposed to a higher dose ofradiation than planned.

FIG. 5 is a flowchart illustrating an MRgRT process 500 consistent withimplementations of the current subject matter. Referring to FIGS. 1, 2,and 5, the MRgRT process 500 can be performed by the MRgRT system 100described with respect to FIG. 1.

The MRgRT system 100 performs system calibration (502). For example, acalibrated output of the radiation therapy head 122 and measuredradiation therapy calibration data can be input into the MRgRT system100 when installing, commissioning, reconfiguring, and/or updating theMRgRT system 100. In addition, data for calibrating the MRI system 128can also be acquired and/or computed. Data for calibrating the MRgRTsystem 100 including the MRI system 128 can include, for example, butnot limited to, dosimetric output of cobalt sources (e.g. if theradiation therapy is performed using a radioisotope source) in areference geometry as required by calibration protocols, relative doseoutput for various field sizes, 1-3 dimensional dose distribution dataof defined beam geometries, and MRI phantom data. The user interface 130can be configured to display at least a portion of the calibration datain overlay, percent difference, and absolute difference. Additionally,the MRgRT system 100 can also store the calibration data (e.g., in thefirst data store 142 and/or the second data store 144) and/or output thecalibration data (e.g., via the printer 136). Integrity of thecalibration data can be ensured by storing redundant copies of thecalibration data and/or applying a cyclically redundant checksumalgorithm.

The MRgRT system 100 can register a user (504). A user (e.g., aradiotherapist) can be required to register prior to operating the MRgRTsystem 100. User registration can include recording one or more forms ofidentification information including, for example, but not limited to,username, password, photograph, and biometrics. At least some users canbe defined as administrative users having the capability to setprivileges and tasks for other users with respect to the MRgRT system100. Access to the MRgRT system 100 can require successful userregistration and authentication. However, in some exampleimplementations, a user can bypass user registration and/orauthentication by providing one or more forms of identificationinformation including, for example, but not limited to, a photograph andbiometrics.

The MRgRT system 100 can register a patient (506). A patient can berequired to register in order to undergo medical imaging and/orradiation therapy treatments administered by the MRgRT system 100.Patient registration can include recording one or more forms ofidentification information including, for example, but not limited to,patient name, password, photograph, and biometrics. In addition, patientregistration can include collecting personal data including, forexample, but not limited to, age, date of birth, gender, weight, race,address, medical data, treatment instructions, contact information, andA/V entertainment preferences.

Prior to undergoing medical imaging and/or receiving radiation therapytreatments, the MRgRT system 100 can require patient authenticationbased on identification information including, for example, but notlimited to, patient name, date of birth, social security number, photoidentification, and biometrics. In some example implementations, in anemergency situation (e.g., an emergent spinal cord compression), patientregistration and/or authentication can be bypassed.

The MRgRT system 100 generates a first treatment plan for the patient(508). Consistent with implementations of the current subject matter,treatment planning includes a plurality of operations including, forexample, but not limited to, MRI image acquisition, contouring (e.g., ofROIs and/or OARs), prescription, and delivery configuration. In someimplementations of the current subject matter, the planned treatment caninclude IMRT. As such, treatment planning can further include IMRTconfigurations.

In some example implementations, a gating mechanism can be deployedduring radiation delivery. The gating mechanism monitors the positionsof anatomical structures (e.g., ROIs and/or OARs) using MRI imagescaptured by the MRgRT system 100 (e.g., the MRI system 128) during thedelivery of radiation and suspends radiation delivery based on spatialand/or temporal “gates.” For example, the gating mechanism can beconfigured to suspend radiation delivery in the event that an ROI or anOAR shifts and remains across of one or more spatial gates (e.g., 3millimeters (mm)) for a length of time in excess of the temporal gate(e.g., 3 seconds). As such, the first treatment plan can includedefinitions of one or more spatial and/or temporal gates.

One or more spatial gates can be defined based on a baseline set of MRIimages depicting the default or resting positions of a patient'sanatomical structures (e.g., ROIs and/or OARs). The MRgRT system 100 canprovide, via the user interface 130, a graphic user interface (GUI) fora user (e.g., a radiologist) to indicate the position of one or morespatial gates on the baseline set of MRI images.

In some implementations of the current subject matter, one or morespatial gates can be set based on a patient's treatment plan (e.g., thefirst treatment plan) to indicate a region that is expected to receive ahigh dose of radiation. Alternately or in addition, the user can set oneor more spatial gates based on overlap between the patient's anatomicalstructures (e.g., ROIs and OARs) as depicted in the MRI images and thoseregions expecting to receive high radiation doses. The MRgRT system 100can provide tools to enables the user to visually set one or morespatial gates based on planar or volumetric representations of ROIs(e.g., generated based on the MRI images) and/or regions expecting toreceive high doses of radiation. In addition, a spatial gate can be setwith fractional gating parameters such that the spatial gate istriggered based on a fractional or percentage overlap in a 2D or 3Dregion. Advantageously, spatial gates ensure that an ROI is exposed toradiation only when the ROI is within the gated region subject to highradiation dose. Alternately or in addition, the gates can also ensurethat an OAR is spared from being exposed to a high radiation dose whenthe OAR enters the gated region subject to high radiation dose.

In some implantations of the current subject matter, the user can alsoset and assign temporal gates to one or more spatial gates. The temporalgates impose a numerical time delay such that a spatial gate istriggered by patient motions (e.g., changes in patient organ geometry)that are maintained over a threshold period of time (e.g., 3 seconds).

Alternately or in addition, in some implementations of the currentsubject matter, an interlock mechanism can be deployed during radiationdelivery. The interlock mechanism is configured to suspend radiationdelivery in response to detecting significant and/or excessive patientmotion (e.g., change in patient organ geometry) in MRI images (e.g.,planar) captured by during the delivery of radiation. As such, the firsttreatment plan can also include one or more thresholds triggering theinterlock mechanism.

Consistent with implementations of the current subject matter, theinterlock mechanism can operate based on fast numerical evaluations ofimage characteristics including, for example, but not limited to, imageintensity (e.g., of MM images). For example, the interlock mechanism canoperate based on loss of image intensity (e.g. blank images), totalchange in pixel intensity between consecutive images or image sets,and/or large changes in variance between consecutive images or imagesets. Changes in image intensity can indicate that the MRI system 128 isnot operating correctly and/or rapid and excessive patient motion.Accordingly, the delivery of radiation can be terminated until thecondition is resolved such as when rapid and excessive patient motionhas ceased.

The MRgRT system 100 administers radiation therapy treatment to thepatient based at least in part on the first treatment plan (510).Consistent with implementations of the current subject matter, treatmentadministration can include a plurality of operations including, forexample, but not limited to, initial and/or continued adjustments ofpatient position (e.g., on the patient couch 124), MRI, and radiationdelivery.

In one implementation of the current subject matter, the MRgRT system100 simultaneously delivers radiation (e.g., via the radiation therapyhead 122) and performs MM (e.g., using the MRI system 128).Advantageously, MM images captured during radiation delivery can be usedto detect patient motion. The MRgRT system 100 can control the deliveryof radiation to a patient based on patient motion detected duringradiation delivery.

In some implementations of the current subject matter where a gatingmechanism is deployed during radiation delivery, treatmentadministration can further include operations to recommence radiationdelivery that has been suspended by the gating mechanism. Alternately orin addition, when an interlock mechanism is deployed during radiationdelivery, treatment administration can also include operations torecommence radiation delivery that has been suspended by the interlockmechanism. For example, the MRgRT system 100 can recommence radiationdelivery when one or more conditions causing the suspension of radiationdelivery has been resolved (e.g., cessation of patient motion,anatomical structure returns within spatial gates).

In some implementations of the current subject matter, the MRgRT system100 is configured to store (e.g., in the first data store 142 and/or thesecond data store 144) at least a portion of the data collected (e.g.,MRI images captured by the MRI system 128) during radiation delivery.For example, data collected from a patient's earlier radiation therapytreatment sessions can be used to generate subsequent treatment plansfor the patient.

The MRgRT system 100 computes an actual dose of radiation delivered tothe patient based on MRI images captured during radiation therapy (512).The actual dose of radiation delivered to the patient can be affected bypatient motion (e.g., shift in patient organ geometry) during thedelivery of radiation and interruptions to radiation delivery caused bythe gating mechanism and/or the interlock mechanism.

The MRgRT system 100 can compute actual dose by performing deformableimage registration to identify anatomical structures (e.g., ROIs, OARS)that demonstrated motion exceeding one or more thresholds duringradiation delivery. Additionally, in some implementations of the currentsubject matter, the MRgRT system 100 can compute actual dosage by alsoidentifying anatomical structures that were exposed to radiation. TheMRgRT system 100 can generate one or more dose volume histograms (DVH)reflecting the actual dosage delivered to the patient.

The MRgRT system 100 generates a second treatment plan for the patientbased on the actual dose of radiation delivered (514). Consistent withimplementations of the current subject matter, the MRgRT system 100 cangenerate a second treatment plan for subsequent radiation therapytreatments based on the actual dose of radiation that was delivered to apatient during one or more previous radiation therapy treatments.

The second treatment plan can include changes to the prescription and/ordelivery configuration indicated by the first treatment plan including,for example, but not limited to, increasing radiation dose to an ROIthat received insufficient doses of radiation during earlier radiationtherapy treatments, decreasing radiation dose to an OAR exposed to anexcessive doses of radiation, changing beam placement, and changing IMRTconfigurations.

In some implementations of the current subject matter, generating thesecond treatment plan can further include acquiring additional MRIimages (e.g., 4D MRI images collected during radiation delivery). TheMRgRT system 100 can generate the second treatment plan to includeadditional adjustments to the prescription indicated by the firsttreatment plan based on the MRI images. The second treatment plan canfurther include changes to one or more gates (e.g., spatial, temporal)and/or one or more interlock thresholds defined in the first treatmentplan for the interlock mechanism.

The MRgRT system 100 generates a comparison of the first treatment planand the second treatment plan (516). Consistent with implementations ofthe current subject matter, the MRgRT system 100 can generate aside-by-side comparison of a plurality of treatment plans. Multipletreatment plans can be compared with respect to plan parametersincluding, for example, but not limited to, DVHs, hot and cold spots indose distribution, and radiation beam parameters (e.g., duration,segment quantity, angle, isocenter radiological depth).

The MRgRT system 100 can provide alerts when the discrepancy between twotreatment plans exceeds one or more thresholds. For example, the MRgRTsystem 100 can display (e.g., on the display 132 coupled to the userinterface 130) dose distributions orthogonally from an MRI image set ofthe patient. The MRgRT system 100 can indicate differences in dosedistribution between multiple treatment plans including by displaying anoverlay of the DVHs associated with various treatment plans.

One or more operations of the process 500 can be performed in adifferent order than shown without departing from the scope of thepresent disclosure. Moreover, one or more operations of the process 500can be repeated and/or omitted without departing from the scope of thepresent disclosure.

FIG. 6 is a flowchart illustrating a process 600 for treatment planningconsistent with implementations of the current subject matter. Referringto FIGS. 1, 5, and 6, the process 600 can be performed by the MRgRTsystem 100 and can implement operation 508 and/or operation 516 of theprocess 500 described with respect to FIG. 5.

The MRgRT system 100 receives at least one MRI image set (602). TheMRgRT system 100 can require at least one MRI image set in order togenerate a treatment plan. In some implementations of the currentsubject matter, the MRgRT system 100 can receive multimodality MRI imagesets, which integrates various different types of medical imaging (e.g.,MRI, CT, positron emission tomography (PET), ultrasound).

The MRgRT system 100 defines one or more anatomical structure based atleast in part on the MRI image set (604). In some implementations of thecurrent subject matter, the MRgRT system 100 can automatically determinethe contours of one or more of a patient's ROIs and OARs. For example,the MRgRT system 100 performs auto contouring based on anonymousexisting data sets and/or earlier data sets from the patient. The MRgRTsystem 100 can require automatically generated contours to be manuallyvalidated.

Automatic contours can be a deforming contour or a non-deformingcontour. A deforming contour adjusts its shape and/or volume to matchthe anatomical structure (e.g., ROI, OAR) when placed on an MRI image.Conversely, a non-deforming contour retains its shape and volume whensuperimposed upon an MRI image. A non-deforming contour is adaptedtracking a region of malignant cells (e.g., clinical targets) thatrequire the same or higher dosage even when the region is receding orhas vanished.

Alternately or in addition, the MRgRT system 100 can also provide, viathe user interface 130, one or more mechanisms for manually segmentingand contouring the patient's anatomy including, for example, but notlimited to, outlining tools and voxel painting tools. The MRgRT system100 can provide a library of anatomical structure names, includingcustom names added by one or more users, for labeling defined ROIsand/or OARs.

In some implementations of the current subject matter, an anatomicalstructure can be defined as an intra-fraction MRI image target volume(ITV). The MRgRT system 100 can generate an ITV as the union of ananatomical structure depicted throughout an MRI image set. Alternately,the MRgRT system 100 can generate an ITV as the time weighted average ofthe anatomical structure depicted throughout an MRI image set. Newlycreated ITVs can be compared to existing ITVs in the orthogonal views onthe original MRI image set to create a set of corresponding segmentationcontours.

In some implementations of the current subject matter, multiple sets ofcontours (e.g., automatic and/or manual) can be available and/or createdfor a single anatomical structure. For example, the MRgRT system 100 canreceive multiple sets of MRI images throughout the course of radiationtherapy treatment. As such, the MRgRT system 100 can provide at leastsome of the contours (e.g., via the user interface 130) in a manner thatenables a user to compare the different contours. For example, the MRgRTsystem 100 can provide at least some of the contours in an overlay withaxial, sagital, and/or coronal orthogonal views. Alternately or inaddition, the different contours can be shown as voxels in a color washdisplay.

The MRgRT system 100 generates a prescription (606). Consistent withimplementations of the current subject matter, the prescription caninclude radiation doses (e.g., dose-volume, dose to points) to bedelivered to a patient's ROIs and margins for expansion. Theprescription can further include various tolerances that include, forexample, but not limited to, dose-volume constraints for OARs. Thevarious tolerances can set limits used for dose prediction and on-tabletreatment plan re-optimization during the administration of radiationtherapy treatment.

In some implementations of the current subject matter, the prescriptioncan also include one or more spatial and temporal gates to be appliedwhen the gating mechanism is deployed during the administration ofradiation therapy treatment. The one or more spatial gates can bedetermined based on MRI images captured by the MRgRT system 100 (e.g.,the MRI system 128) during the delivery of radiation.

The prescription can also include additional treatment parametersincluding, for example, but not limited to, requirements or prohibitionsfor planar imaging, volumetric imaging, dose prediction, on-tablere-optimization, 4D MRI image data acquisition, MRI image target volume(ITV) target generation, planar gating, and delivered dose evaluation.

Consistent with implementations of the current subject matter, theradiation doses and tolerances specified in the prescription can bedetermined based on the cumulative actual radiation doses delivered tothe patient (e.g., ROIs and OARs) as determined by the MRgRT system 100(e.g., the dose reconstruction cluster 150). The actual dose ofradiation that was delivered a patient can be determined using MRIimages (e.g., 4D MRI images) captured by the MRgRT system 100 (e.g., theMRI system 128) prior to, during, and/or post the administration ofradiation therapy.

The MRgRT system 100 generates one or more radiation deliveryconfiguration (608). Consistent with implementations of the currentsubject matter, the delivery configuration can include, for example, butnot limited to, isocenter placement, and beam and/or IMRT or CRTconfiguration.

The MRgRT system 100 can provide a GUI via the user interface 130 toallow a user (e.g., radiotherapist) to manually place one or moreisocenters indicating points on an ROI where radiation beams should passthrough.

In some implementations of the current subject matter, the MRgRT system100 can provide default beam configurations or templates for use withIMRT and/or CRT to assist a user in beam configuration. For example,default beam configurations or templates can be provided for one or morecommon ROIs including, for example, but not limited to, breast withtangents, breast with tangents and nodal irradiation, head and neck withlow neck field, head and neck with separate low neck field, centralnervous system, craniospinal, lung, prostate, whole pelvis, right andleft hemi pelvis, whole pelvis with or without para-aortics, wholebrain, vertebral body, mantle fields, and whole body fields.

Alternately or in addition, a user can create and save custom beamconfigurations as new templates. For example, the user can manuallyplace one or more radiation beams using a beam-eye-view display providedby the MRgRT system 100. The user can place the radiation beams in aplurality of placement modes including, for example, but not limited to,3-beam placement and single beam placement. In some implementations ofthe current subject matter, the MRgRT system 100 can provide beamtransit time corresponding to the placement of individual radiationbeams.

In some implementations of the current subject matter, one or more ofplaced radiation beams can be selected for IMRT. When a radiation beamis selected for IMRT, the MRgRT system 100 can provide a GUI for a userto indicate IMRT configuration parameters including, for example, butnot limited to, prescription doses for ROIs, tolerance doses for OARs,and the relative importance of the ROIs and the OARs. In someimplementations of the current subject matter, the MRgRT system 100 canprovide IMRT templates that include optimized models for administeringIMRT. The templates include predefined values that have beendemonstrated to produce ideal results in previous cases. Alternately, auser can also create and save custom IMRT configurations as IMRTtemplates.

Consistent with implementations of the current subject matter, the MRgRTsystem 100 can optimize an IMRT configuration by performing one or moreoperations including, for example, but not limited to, fluence mapoptimization (e.g., performed using beamlet dose calculation), leafsequencing, and segment ordering optimization. The MRgRT system 100 canfurther optimize the IMRT configuration by performing Monte Carlosimulations.

In some implementations of the current subject matter, the MRgRT system100 performs a “warm start” optimization based on an original IMRTconfiguration and an original set of IMRT configuration parameters.Advantageously, a “warm start” optimization ensures that the optimizedIMRT configuration is similar to the original IMRT configuration devisedfor a patient. However, adjusting one or more IMRT configurationparameters can steer the optimized IMRT configuration towards a moredesirable, albeit divergent, solution.

The MRgRT system 100 generates one or more dose predictions based atleast in part on the prescription and delivery configuration (610).Consistent with implementations of the current subject matter, the MRgRTsystem 100 can generate a dose prediction by applying the prescriptionand the delivery configuration to MRI images captured by the MRgRTsystem 100 (e.g., the MRI system 128) in order to detect any interplayand/or aliasing effects on dose delivery.

The MRgRT system 100 determines whether the dose predication meets oneor more clinical objectives (611). If the MRgRT system 100 determinesthat the dose prediction meets the one or more clinical objectives(611-Y), the MRgRT system 100 generates a treatment plan that includesthe prescription and the delivery configuration (612). Clinicalobjectives can include, for example, but not limited to, dose-volumeconstraints on a patient's anatomical structures (e.g., ROIs and OARs),minimum allowed doses for the patient's anatomical structures, maximumdoses for the patient's anatomical structures, biologically effectivedoses or dose volume constraints, tumor control probabilities, andnormal tissue (e.g., OAR) complication probabilities.

Alternately, if the MRgRT system 100 determines that the dose predictiondoes not meet the one or more clinical objectives (611-N), the MRgRTsystem 100 modifies at least one of the prescription and the deliveryconfiguration (614). The MRgRT system 100 generates a dose predictionbased on the prescription and the delivery configuration (610) anddetermines whether the dose prediction meets one or more clinicalobjectives (611).

In some implementations of the current subject matter, the MRgRT system100 can be configured to perform the process 600 a priori (i.e., priorto patient arrival). Alternately or in addition, the MRgRT system 100can be configured to perform the process 600 “on-table” (e.g., while apatient is present on the patient couch 124). Advantageously, the MRgRTsystem 100 is capable of performing the process 600 to generate atreatment plan in an efficient and timely manner (e.g., less than 2minutes) for on-table treatment planning.

One or more operations of the process 600 can be performed in adifferent order than shown without departing from the scope of thepresent disclosure. Moreover, one or more operations of the process 600can be repeated and/or omitted without departing from the scope of thepresent disclosure.

FIG. 7 is a flowchart illustrating a process 700 for administeringradiation therapy consistent with implementations of the current subjectmatter. Referring to FIGS. 1, 5, and 7, the process 700 can be performedby the MRgRT system 100 and can implement operation 510 of the process500 described with respect to FIG. 5.

The MRgRT system 100 adjusts the position of a patient (702). Forexample, the MRgRT system 100 can adjust the position of the patientincluding by adjusting the position of the patient couch 124. In someimplementations of the current subject matter, the MRgRT system 100 canadjust patient position using a laser system to identify 3 orthogonal“landing points” marked on the skin of the patient. The MRgRT system 100can store adjustments made during earlier radiation therapy sessions andautomatically apply the same adjustments during subsequent radiationtherapy sessions.

Additionally, the MRgRT system 100 can assist a user (e.g., aradiotherapist) in performing manual patient adjustments. For instance,the MRgRT system 100 can provide alerts if the lateral and/or verticallimits of couch motion are exceeded or if the patient (or the patientcouch 124) is too close to the gantry 120 and/or the radiation therapyhead 122. The MRgRT system 100 can also display (e.g., via the display132 coupled to the user interface 130) the location of the isocenter aswell as project the radiation beams placed according to the treatmentplan. Additionally, the MRgRT system 100 can verify that the patient isproperly positioned by obtaining one or more of orthogonal pilot scansand current primary planning volumes.

The MRgRT system 100 simultaneously delivers radiation and performs MRI(704). Consistent with implementations of the current subject matter,the MRgRT system 100 delivers radiation (e.g., via the radiation therapyheads 122) to a patient (e.g., on the patient couch 124) while alsocapturing MM images (e.g., using the MRI system 128).

In some implementations of the current subject matter, the MRgRT system100 can selectively save MRI images captured during radiation delivery.For example, the MRgRT system 100 can remove MRI images captured whenradiation delivery is suspended (e.g., by the gating and/or interlockmechanism) and/or consolidate MRI images that do not depict patientmotion in excess of a threshold (e.g., 2 mm).

The MRgRT system 100 determines whether one or more gates are triggeredbased on at least a portion of the MRI images captured during thedelivery of radiation (705). Consistent with implementations of thecurrent subject matter, a gating mechanism can be deployed duringradiation delivery. The gating mechanism monitors the positions of oneor more anatomical structures (e.g., ROIs and/or OARs) during radiationdelivery relative to one or more spatial gates. The position of ananatomical structure can trigger a spatial gate if that anatomicalstructure shifts outside of the spatial gate (e.g., 3 mm). Additionally,a temporal gate can be triggered if the anatomical structure remainsoutside of the spatial gate for a length of time in excess of thetemporal gate (e.g., 3 seconds).

The MRgRT system 100 may determine that one or more gates are nottriggered based on at least a portion of the MRI images captured duringthe delivery of radiation (705-N). For example, the position of theanatomical structure may remain within the one or more spatial gates.Alternately, the position of the anatomical structure may shift outsideof the one or more spatial gate but not for a period of time thatexceeds a temporal gate. As such, the MRgRT system 100 determineswhether patient motion exceeds one or more interlock thresholds based onat least a portion of the MM images captured during the delivery ofradiation (707). In some implementations of the current subject matter,an interlock mechanism can be deployed during radiation delivery. Theinterlock mechanism detects patient motion based on planar MRI imagesand suspends radiation delivery in response to detecting patient motionthat exceeds one or more thresholds.

If the MRgRT system 100 determines that patient motion exceeds one ormore interlock thresholds (707-Y), the MRgRT system 100 suspends thedelivery of radiation (708). Alternately, if the MRgRT system 100determines that patient motion does not exceed one or more interlockthresholds (707-N), the MRgRT system 100 continues to simultaneouslydeliver radiation and perform medical imaging (704).

Alternately, if the MRgRT system 100 determines that one or more gatesare triggered based at least a portion of the MRI images captured duringthe delivery of radiation (705-Y), the MRgRT system 100 suspends thedelivery of radiation (708). For example, the position of the anatomicalstructure may shift outside of the one or more spatial gates.Additionally, the position of the anatomical structure may shift outsideof the one or more spatial gates for a period of time exceeding atemporal gate. Accordingly, the MRgRT system 100 can determine that oneor more gates are triggered and suspend radiation delivery.

The MRgRT system 100 determines whether one or more conditions causingthe suspension of radiation delivery are resolved (709). For example,the MRgRT system 100 can determine whether the anatomical structure hasreturned to a position inside of the spatial gate. The MRgRT system 100can also determine whether patient motion in excess of the one or morethresholds has ceased.

If the MRgRT system 100 determines that the one or more conditionscausing the suspension of radiation delivery are resolved (709-Y), theMRgRT system 100 recommences delivery of radiation (710). The MRgRTsystem 100 continues to simultaneously deliver radiation and performmedical imaging (704). Alternately, if the MRgRT system 100 determinesthat the one or more conditions triggering the one or more gates are notresolved (709-N), the MRgRT system 100 will continue to suspend thedelivery of radiation (706).

One or more operations of the process 700 can be performed in adifferent order than shown without departing from the scope of thepresent disclosure. Moreover, one or more operations of the process 700can be repeated and/or omitted without departing from the scope of thepresent disclosure.

FIG. 8 is a flowchart illustrating a process 800 for dose computationconsistent with implementations of the current subject matter. Referringto FIGS. 1, 7, and 8, the process 800 can be performed by the MRgRTsystem 100 (e.g., the dose reconstruction cluster 180) and can implementoperation 512 of the process 500 described with respect to FIG. 5.

The MRgRT system 100 performs deformable image registration on MRIimages captured during the delivery of radiation (802). For example, theMRgRT system 100 can perform deformable image registration on a seriesof MRI images captured by the MRI system 128 prior to, during, or postthe administration of radiation therapy. In some implementations of thecurrent subject matter, the MRgRT system 100 can track the absolutedeviation of one or more anatomical structures (e.g., ROIs and OARs)from initial locations throughout the delivery of radiation.

The MRgRT system 100 identifies one or more anatomical structures fordose computation (804). The actual dose of radiation delivered isaffected by patient motion (e.g., shift in patient organ geometry)during the delivery of radiation. Thus, in some implementations of thecurrent subject matter, the MRgRT system 100 can flag anatomicalstructures that have moved in excess of a threshold for dose computationwhereas anatomical structures that did not demonstrate motion exceedingthe threshold are bypassed for dose computation. Alternately or inaddition, the MRgRT system 100 can correlate the MRI images captured bythe MRgRT system 100 (e.g., the MRI system 128) with radiation beamshapes and fluences through the patient to determine one or moreanatomical structures that were not exposed to radiation. The MRgRTsystem 100 can flag anatomical structures that were exposed to radiationfor dose computation while anatomical structures that were not exposedto radiation can be bypassed for dose computation.

The MRgRT system 100 generates an initial computation of the actualradiation doses delivered to the one or more anatomical structuresidentified for dose computation (806). Consistent with implementationsof the current subject matter, the MRgRT system 100 can perform a scaleddensity finite sized pencil beam algorithm to generate the initialcomputation of the actual radiation doses delivered. Alternately or inaddition, the MRgRT system 100 can perform a time dependent Monte Carlosimulation that incorporates control data and MRI images captured by theMRgRT system 100 (e.g., the MRI system 128) during radiation delivery.

In addition to patient motion, the actual dose of radiation delivered tothe patient can also be affected by interruptions to the delivery ofradiation caused by the gating mechanism and/or the interlock mechanism.For example, the gating mechanism and/or the interlock mechanism cancause a series of suspensions in radiation delivery thereby changing theactual dose of radiation delivered to the patient including, forexample, but not limited to, shutter dose effects and truncation errorsfor radiation doses below a safely deliverable threshold. Accordingly,the MRgRT system 100 is configured to generate an initial computationthat accounts for the effects of the interruptions to radiation deliverycaused by the gating mechanism and/or the interlock mechanism. Forexample, the MRgRT system 100 can record and account dose variationsduring radiation delivery and account for such variations when computingthe actual dose of radiation delivered to the patient.

The MRgRT system 100 computes an uncertainty associated with the initialcomputation (808). The MRgRT system 100 computes one or more actualradiation doses based at least in part on the initial computation andthe uncertainty associated with the initial computation (810).Uncertainty associated with the initial computation of radiation dosescan arise due to the random nature of Monte Carlo simulations.Additionally, uncertainty associated with the initial computation canarise during the course of deformable image registration. For example,deformable image registration provides a probabilistic outcome based onthe absolute magnitude of the deformation and the change in connectivityin neighboring voxels. As such, the MRgRT system 100 can compute theactual radiation dose by interpolating a distribution of the initialcomputation and the uncertainty associated with the initial computation.

The MRgRT system 100 generates one or more DVHs reflecting the actualdoses delivered (812). The MRgRT system 100 compares the DVHs associatedwith the actual delivered dose with DVHs associated with a correspondingtreatment plan (814). The MRgRT system 100 provides an alert if thecomparison between the DVHs associated with the actual delivered dosesand the DVHs associated with a corresponding treatment plan indicates adifference in excess of one or more thresholds (814). For example, theMRgRT system 100 can issue a warning (e.g., to a clinician) in the eventthat a discrepancy between the actual radiation dose delivered to apatient and the radiation dose prescribed in a treatment plan exceedsone or more thresholds including, for example, but not limited to,coverage volume, and hot and cold spots in dose distribution.

One or more operations of the process 800 can be performed in adifferent order than shown without departing from the scope of thepresent disclosure. Moreover, one or more operations of the process 800can be repeated and/or omitted without departing from the scope of thepresent disclosure.

FIG. 9 is a flowchart illustrating a process 900 for administeringradiation therapy consistent with implementations of the current subjectmatter. Referring to FIGS. 1, 5, and 9, the process 900 can be performedby the MRgRT system 100 and can implement operation 510 of the process500 described with respect to FIG. 5.

The MRgRT system 100 simultaneously delivers radiation and performs MRI(902). The MRgRT system 100 determines whether one or more gates aretriggered based on at least a portion of the MRI images captured duringthe delivery of radiation (903). For example, the MRgRT system 100 canuse the MRI images captured during the delivery of radiation todetermine whether one or more spatial and/or temporal gates aretriggered.

The MRgRT system 100 can determine that one or more gates are nottriggered based on at least a portion of the MRI images captured duringthe delivery of radiation (903-N). For example, the position of theanatomical structure may remain within the one or more spatial gates.Alternately, the position of the anatomical structure may shift outsideof the one or more spatial gate but not for a period of time thatexceeds a temporal gate. As such, the MRgRT system continues to deliverradiation and perform MRI (902).

Alternately, if the MRgRT system determines that one or more gates aretriggered based on at least a portion of the MRI images captured duringthe delivery of radiation (903-Y), the MRgRT system 100 suspends thedelivery of radiation (904).

One or more operations of the process 900 can be performed in adifferent order than shown without departing from the scope of thepresent disclosure. Moreover, one or more operations of the process 900can be repeated and/or omitted without departing from the scope of thepresent disclosure.

Implementations of the present disclosure can include, but are notlimited to, methods consistent with the descriptions provided above aswell as articles that comprise a tangibly embodied machine-readablemedium operable to cause one or more machines (e.g., computers, etc.) toresult in operations implementing one or more of the described features.Similarly, computer systems are also described that can include one ormore processors and one or more memories coupled to the one or moreprocessors. A memory, which can include a computer-readable storagemedium, can include, encode, store, or the like one or more programsthat cause one or more processors to perform one or more of theoperations described herein. Computer implemented methods consistentwith one or more implementations of the current subject matter can beimplemented by one or more data processors residing in a singlecomputing system or multiple computing systems. Such multiple computingsystems can be connected and can exchange data and/or commands or otherinstructions or the like via one or more connections, including but notlimited to a connection over a network (e.g. the Internet, a wirelesswide area network, a local area network, a wide area network, a wirednetwork, or the like), via a direct connection between one or more ofthe multiple computing systems, etc.

One or more aspects or features of the subject matter described hereincan be realized in digital electronic circuitry, integrated circuitry,specially designed application specific integrated circuits (ASICs),field programmable gate arrays (FPGAs) computer hardware, firmware,software, and/or combinations thereof. These various aspects or featurescan include implementation in one or more computer programs that areexecutable and/or interpretable on a programmable system including atleast one programmable processor, which can be special or generalpurpose, coupled to receive data and instructions from, and to transmitdata and instructions to, a storage system, at least one input device,and at least one output device. The programmable system or computingsystem can include clients and servers. A client and server aregenerally remote from each other and typically interact through acommunication network. The relationship of client and server arises byvirtue of computer programs running on the respective computers andhaving a client-server relationship to each other.

These computer programs, which can also be referred to programs,software, software applications, applications, components, or code,include machine instructions for a programmable processor, and can beimplemented in a high-level procedural language, an object-orientedprogramming language, a functional programming language, a logicalprogramming language, and/or in assembly/machine language. As usedherein, the term “machine-readable medium” refers to any computerprogram product, apparatus and/or device, such as for example magneticdiscs, optical disks, memory, and Programmable Logic Devices (PLDs),used to provide machine instructions and/or data to a programmableprocessor, including a machine-readable medium that receives machineinstructions as a machine-readable signal. The term “machine-readablesignal” refers to any signal used to provide machine instructions and/ordata to a programmable processor. The machine-readable medium can storesuch machine instructions non-transitorily, such as for example as woulda non-transient solid-state memory or a magnetic hard drive or anyequivalent storage medium. The machine-readable medium can alternativelyor additionally store such machine instructions in a transient manner,such as for example as would a processor cache or other random accessmemory associated with one or more physical processor cores.

To provide for interaction with a user, one or more aspects or featuresof the subject matter described herein can be implemented on a computerhaving a display device, such as for example a cathode ray tube (CRT) ora liquid crystal display (LCD) or a light emitting diode (LED) monitorfor displaying information to the user and a keyboard and a pointingdevice, such as for example a mouse or a trackball, by which the usermay provide input to the computer. Other kinds of devices can be used toprovide for interaction with a user as well. For example, feedbackprovided to the user can be any form of sensory feedback, such as forexample visual feedback, auditory feedback, or tactile feedback; andinput from the user can be received in any form, including, but notlimited to, acoustic, speech, or tactile input. Other possible inputdevices include, but are not limited to, touch screens or othertouch-sensitive devices such as single or multi-point resistive orcapacitive trackpads, voice recognition hardware and software, opticalscanners, optical pointers, digital Mill image capture devices andassociated interpretation software, and the like.

In the descriptions above and in the claims, phrases such as “at leastone of” or “one or more of” may occur followed by a conjunctive list ofelements or features. The term “and/or” may also occur in a list of twoor more elements or features. Unless otherwise implicitly or explicitlycontradicted by the context in which it used, such a phrase is intendedto mean any of the listed elements or features individually or any ofthe recited elements or features in combination with any of the otherrecited elements or features. For example, the phrases “at least one ofA and B;” “one or more of A and B;” and “A and/or B” are each intendedto mean “A alone, B alone, or A and B together.” A similarinterpretation is also intended for lists including three or more items.For example, the phrases “at least one of A, B, and C;” “one or more ofA, B, and C;” and “A, B, and/or C” are each intended to mean “A alone, Balone, C alone, A and B together, A and C together, B and C together, orA and B and C together.” Use of the term “based on,” above and in theclaims is intended to mean, “based at least in part on,” such that anunrecited feature or element is also permissible.

The subject matter described herein can be embodied in systems,apparatus, methods, and/or articles depending on the desiredconfiguration. The implementations set forth in the foregoingdescription do not represent all implementations consistent with thesubject matter described herein. Instead, they are merely some examplesconsistent with aspects related to the described subject matter.Although a few variations have been described in detail above, othermodifications or additions are possible. In particular, further featuresand/or variations can be provided in addition to those set forth herein.For example, the implementations described above can be directed tovarious combinations and subcombinations of the disclosed featuresand/or combinations and subcombinations of several further featuresdisclosed above. In addition, the logic flows depicted in theaccompanying figures and/or described herein do not necessarily requirethe particular order shown, or sequential order, to achieve desirableresults. Other implementations can be within the scope of the followingclaim.

What is claimed is:
 1. A method for magnetic resonance (MR) guidedradiation therapy (MRgRT), the method comprising: simultaneously usingone or more radiation therapy heads to deliver radiation and an MRimaging (MRI) system to perform MM; using a processor to determinewhether one or more gates are triggered based on at least a portion ofMRI images captured during the delivery of radiation; and in response todetermining that one or more gates are triggered based on at least aportion of the MRI images captured during the delivery of radiation,suspending the delivery of radiation.
 2. The method of claim 1, whereinthe one or more gates includes a spatial gate that is triggered when oneof a region of interest (ROI) and an organ at risk (OAR) shifts acrossthe spatial gate during the delivery of radiation.
 3. The method ofclaim 2, wherein the one or more gates further includes a temporal gatethat is triggered when the one of the ROI and the OAR remains across thespatial gate for a length of time exceeding the temporal gate.
 4. Themethod of claim 1, further comprising: in response to determining thatone or more gates are not triggered based on at least a portion of theMM images captured during the delivery of radiation, continuing tosimultaneously use the one or more radiation therapy heads to deliverradiation and the MRI system to perform MRI.
 5. The method of claim 1,further comprising: determining whether patient motion exceeds one ormore interlock thresholds based on at least a portion of the MRI imagescaptured during the delivery of radiation; and in response todetermining that patient motion exceeds one or more interlock thresholdsbased on at least a portion of the MRI images captured during thedelivery of radiation, suspending the delivery of radiation.
 6. Themethod of claim 1, further comprising: determining whether one or moreconditions causing the suspension of radiation delivery is resolved; andin response to determining that the one or more conditions causing thesuspension of radiation delivery is resolved, recommencing the deliveryof radiation.
 7. The method of claim 1, wherein radiation delivery isperformed based at least in part on a first treatment plan.
 8. Themethod of claim 7, further comprising generating the first treatmentplan by: receiving at least one MRI image set; defining one or moreanatomical structures; generating a prescription; and generating adelivery configuration.
 9. The method of claim 8, wherein defining theone or more anatomical structures comprises using the processor toautomatically contour one or more of a region of interest (ROI) and anorgan at risk (OAR).
 10. The method of claim 7, further comprisingcomputing an actual dose of radiation delivered.
 11. The method of claim10, wherein the actual dose of radiation is computed based on at leastone of the MRI images captured during the delivery of radiation and oneor more suspensions of radiation delivery due the triggering of the oneor more gates.
 12. The method of claim 10, further comprising generatinga second treatment plan based at least in part on the actual dose ofradiation delivered.
 13. The method of claim 12, wherein generating thesecond treatment plan comprises modifying at least one of a prescriptionand a delivery configuration comprising the first treatment plan. 14.The method of claim 13, wherein the prescription includes one or more ofa radiation dose to be delivered to a region of interest (ROI), a marginfor expansion, a dose-volume constraint for an organ at risk (OAR), atemporal gate, and a spatial gate; and wherein the deliveryconfiguration include at least one of an isocenter placement, radiationbeam configuration, intensity modulated radiation therapy (IMRT)configurations, and conformal radiation therapy (CRT) configurations.15. A magnetic resonance (MR) guided radiation therapy (MRgRT) system,comprising: an MRgRT apparatus comprising one or more radiation therapyheads and an MR imaging (MRI) system, wherein the MRgRT apparatus isconfigured to simultaneously use the one or more radiation therapy headsto deliver radiation and the MRI system to perform MM; and a processorcoupled to the MRgRT apparatus and configured to: determine whether oneor more gates are triggered based on at least a portion of MRI imagescaptured during the delivery of radiation; and in response todetermining that one or more gates are triggered based on at least aportion of the MRI images captured during the delivery of radiation,suspend the delivery of radiation.
 16. The system of claim 15, whereinthe one or more gates includes a spatial gate that is triggered when oneof a region of interest (ROI) and an organ at risk (OAR) shifts acrossthe spatial gate during the delivery of radiation.
 17. The system ofclaim 16, wherein the one or more gates further includes a temporal gatethat is triggered when the one of the ROI and the OAR remains across thespatial gate for a length of time exceeding the temporal gate.
 18. Thesystem of claim 15, wherein the processor is further configured to: inresponse to determining that one or more gates are not triggered basedon at least a portion of the MM images captured during the delivery ofradiation, continue to simultaneously use the one or more radiationtherapy heads to deliver radiation and the MRI system to perform MRI.19. The system of claim 15, wherein the processor is further configuredto: determine whether patient motion exceeds one or more interlockthresholds based on at least a portion of the MRI images captured duringthe delivery of radiation; and in response to determining that patientmotion exceeds one or more interlock thresholds based on at least aportion of the MRI images captured during the delivery of radiation,suspend the delivery of radiation.
 20. The system of claim 15, whereinthe processor is further configured to: determining whether one or moreconditions causing the suspension of radiation delivery is resolved; andin response to determining that the one or more conditions causing thesuspension of radiation delivery is resolved, recommencing the deliveryof radiation.
 21. The system of claim 15, wherein the MRgRT apparatusperforms radiation delivery based at least in part on a first treatmentplan.
 22. The system of claim 21, wherein the processor is furtherconfigured to generate the first treatment plan by: receiving at leastone MRI image set; defining one or more anatomical structures;generating a prescription; and generating a delivery configuration. 23.The system of claim 22, wherein to define the one or more anatomicalstructures, the processor is configured to automatically contour one ormore of a region of interest (ROI) and an organ at risk (OAR).
 24. Thesystem of claim 21, wherein the processor is further configured tocompute an actual dose of radiation delivered.
 25. The system of claim24, wherein the processor is configured to compute the actual dose ofradiation based on at least one of the MRI images captured during thedelivery of radiation and one or more suspensions of radiation deliverydue the triggering of the one or more gates.
 26. The system of claim 24,wherein the processor is further configured to generate a secondtreatment plan based at least in part on the actual dose of radiationdelivered.
 27. The system of claim 26, wherein to generate the secondtreatment plan, the processor is configured to modify at least one of aprescription and a delivery configuration comprising the first treatmentplan.
 28. The system of claim 27, wherein the prescription includes oneor more of a radiation dose to be delivered to a region of interest(ROI), a margin for expansion, a dose-volume constraint for an organ atrisk (OAR), a temporal gate, and a spatial gate; and wherein thedelivery configuration include at least one of an isocenter placement,radiation beam configuration, intensity modulated radiation therapy(IMRT) configurations, and conformal radiation therapy (CRT)configurations.
 29. A method of magnetic resonance (MR) guided radiationtherapy (MRgRT), comprising: receiving a plurality of MR imaging (MRI)images captured by an MRI system during a delivery of radiation by oneor more radiation therapy heads; determining, based on a least a portionof the MRI images, whether one or more gates are triggered; and inresponse to determining that the one or more gates are triggered basedon at least a portion of the MRI images, causing the one or moreradiation therapy heads to suspend delivery of radiation.
 30. The methodof claim 29, wherein the one or more gates includes a spatial gate thatis triggered when one of a region of interest (ROI) and an organ at risk(OAR) shifts across the spatial gate during the delivery of radiation.31. The method of claim 30, wherein the one or more gates furthercomprises a temporal gate that is triggered when the one of the ROI andthe OAR remains across the spatial gate for a length of time exceedingthe temporal gate.
 32. The method of claim 29, further comprising: inresponse to determining that one or more gates are not triggered basedon at least a portion of the MM images captured during the delivery ofradiation, continuing to simultaneously use the one or more radiationtherapy heads to deliver radiation and the MRI system to perform MRI.33. The method of claim 29, further comprising: determining whetherpatient motion exceeds one or more interlock thresholds based on atleast a portion of the MRI images captured during the delivery ofradiation; and in response to determining that patient motion exceedsone or more interlock thresholds based on at least a portion of the MRIimages captured during the delivery of radiation, suspending thedelivery of radiation.
 34. The method of claim 29, wherein the radiationdelivery is performed based at least in part on a first treatment plan.35. The method of claim 34, further comprising: computing an actual doseof radiation delivered based on at least one of the MRI images capturedduring the delivery of radiation and one or more suspensions ofradiation delivery due the triggering of the one or more gates; andgenerating a second treatment plan based at least in part on the actualdose of radiation delivered.